Wiktionary
unjammable
a. Not jammable.
Usage examples of "unjammable".
An arctic storm jammed the unjammable metering station at the pole: Hohbach, their chief of science, thought that a defective casing on the self-repair devices cracked and the equipment froze.
They were the untappable, unjammable, undetectable link which tied together angry men from Riga to Vladivostok.